Male external urinary catheters are commonly manufactured by dip processing or blow molding. Examples of dip processing are set forth in U.S. Pat. Nos. 5,376,085 (silicone rubber), U.S. Pat. No. 5,407,715 (triblock copolymers), U.S. Pat. No. 4,475,910 (latex), U.S. Pat. No. 4,846,909 (latex) and International Publication WO 96/29962 (polyurethane). A combination of injection molding, pull extrusion and blow molding is disclosed in U.S. Pat. No. 5,554,141 (styrene-based block copolymers). Regardless of the method used, the catheters produced by such processes characteristically have the common feature of inner surface contours that mimic or match the contours of the outer surfaces.
Typically, a male external catheter has a generally cylindrical body section or sheath that fits about a wearer's penis and may include a bulbous enlargement at it distal end for extending over the glands, a drain tube section of reduced diameter adapted to be connected to drainage tubing leading to a leg bag or some other urine-receiving receptacle, and a tapered or generally frusto-conical neck section interposed between and connecting the body and drain tube sections. The tapered neck section is frequently provided with a series of annular corrugations or convolutions to permit greater stretchability, bending and twisting of the neck section when the device is in use and to do so with less chance that kinking or obstruction of the lumen might occur. While the corrugations are effective in achieving those objectives, they also result in a construction in which the inner surface of the neck portion, which mimics the corrugations of the outer surface, has the disadvantage of collecting and retaining small amounts of urine within its annular channels or grooves.
The fact that inner and outer surfaces of conventional male external catheters are parallel to each other or follow the same contours also has other disadvantages. Such catheters commonly have smooth-walled drain tube sections that must be pushed over stepped connectors to attach the catheters to urine collection bags. Smooth-walled tubes can be difficult to push onto such connectors but, heretofore, it has not been considered feasible to provide such a drain tube section with a contoured outer surface that facilitates gripping and advancing the section onto a connector while at the same time providing such section with a smooth cylindrical inner surface.